Semiconductor manufacturing involves the formation of integrated circuits (ICs), such as logic circuits and memory circuits. The fabrication of ICs involves forming microscopic three-dimensional structures in semiconductor (e.g., silicon) wafers to define the various circuit components, such as transistors, capacitors, electrical interconnections and electrical isolation features. The electrical interconnections typically run between different levels in the IC as well as within certain levels. The process of forming the ICs involves a large number (e.g., dozens or many dozens) of processing steps from the initial preparation of the wafer to the final packaging of the IC.
In the past, aluminum was the preferred metal for forming electrical interconnections. In 1997, the electrical interconnects were changed to copper due to its smaller resistivity, increased reliability and its ability to form smaller lines than aluminum.
While this change in the interconnect material from aluminum to copper has been advantageous, increasing integration requirements are placing even greater demands on IC performance. It would therefore be advantageous to have systems and methods that can improve the electrical performance of metal interconnects.